The Concrete Manholes, a Symbol of the Modern City
Introduction: What are Concrete Manholes and Why Are they a Symbol of the Modern City?
The history of the manholes is not clear. They are often said to be designed in 1875 by George E. Waring Jr., who was appointed by New York City’s sanitary commission, but it is unclear if his idea was original or copied from European designs.
Concrete manholes were initially installed in order to refill the underground cisterns with fresh water. The cast-iron and steel pipes and steel tanks inside were connected with a system of valves and pumps that would provide a pressurized water supply to the city’s fire-fighting companies.
It is important to note that even though concrete manholes are symbols of modern cities, most people do not know the history behind them, and they may just be seen as an eyesore in their communities.
Different Types of Concrete Manholes and Their Uses
Concrete manholes are structures made from concrete that are used to carry sewage and stormwater. They can be round or square, and there are a few different types of construction depending on the application such as circular, vaulted, or segmental. There are also a number of considerations to consider when choosing the material for your project.
Traditional Concrete Manholes
Concrete manholes are used for drainage of sewage. They are usually cylindrical in shape and are manufactured economically in order to keep the cost low. These structures are made of concrete and buried in the ground. They can be precast or formed and poured in the ground, depending on what the project requires.
Traditional concrete manholes have been the standard for many decades.
However, while concrete manholes are much better than primitive efforts, there are some shortcomings. For example, one issue with concrete manholes is corrosion.
Corrosion can easily ruin concrete sewer systems. It can make a system more susceptible to cracks and leaks, which ultimately increase the chance of water infiltration. This water infiltration can cause irreparable structural damage and render a system inoperable.
One of the main reasons for corrosion in concrete is the presence of oxygen. For example, when water penetrates the concrete, it releases carbon dioxide. The carbon dioxide reacts with the calcium hydroxide to form calcium carbonate and hydrogen carbonate, which are both soluble in water. This causes a chemical reaction that leads to rusting and steel corroding away.
Polymer Concrete Manholes
Polymer concrete manholes are very similar to traditional concrete manholes. The main difference is the composition of the concrete.
Polymer concrete is a type of concrete that has been reinforced with polymers. In the United States, it is patented. The polymer gives polymer concrete a longer lifespan and can withstand extreme heat and cold better than traditional concrete making it an excellent option for different climates.
Polymer concrete is corrosion-proof because it contains an acrylic polymer. This chemical interacts with the alkaline environment and prevents corrosion from happening to the concrete.
The Legacy of the Concrete Manholes on Modern Cities
Manholes are ubiquitous in our urban landscape and they’re also a powerful reminder of how much we rely on this humble design element, no matter where we live. Manholes are found in every city, town, and village that has pipes carrying wastewater away from homes or businesses to treatment facilities or septic tanks.
The legacy of these heavy, gray-colored boxes is all around us, but few people think about them because they’re not always visible unless you bend down to see them up close.
And just as concrete manholes are a symbol of modern cities, polymer concrete manholes are a welcome innovation improving those systems all around us.